code: def test_load_all_singlestage(tmp_dir, dvc):
      (stage1,) = tmp_dir.dvc_gen("foo", "foo")
      dvcfile = load_file(dvc, "foo.dvc")
      assert isinstance(dvcfile, SingleStageFile)
      assert len(dvcfile.stages) == 1
      stages = dvcfile.stages.values()
      assert len(stages) == 1
      assert list(stages) == [stage1]
  
imports: import textwrap
  import pytest
  from dvc.annotations import Annotation
  from dvc.dvcfile import LOCK_FILE, PROJECT_FILE, ParametrizedDumpError, SingleStageFile, load_file
  from dvc.stage.exceptions import StageFileDoesNotExistError
  from dvc.stage.loader import StageNotFound
  from dvc.utils.strictyaml import YAMLValidationError
label_desc: Use image node_id 7 for calling a global function with example usage: test_load_all_singlestage(tmp_dir, dvc) without return types